Enhancement of a Multiple-Input Multiple-Output (MIMO) technology and Coordinated Multipoint Transmission (CoMP) are important ways to accommodate requirements on increasing peak spectrum efficiency and average spectrum efficiency of a Long Term Evolution Advanced (LTE-A) system. In the current Third Generation Partnership Project (3GPP) Evolved Universal Terrestrial Radio Access Network (E-UTRAN) Release 10 (R10) edition, the enhanced MIMO technology is a spatial multiplexing technology supporting eight layers at most, which may adopt a codebook-based precoding solution or a non-codebook-based precoding solution. With principles of a distributed antenna, CoMP reduces interference by using collaboration of multiple base stations, thereby enhancing data spectrum efficiency. As a key technology of LTE-A, CoMP may effectively increase the average throughput of a system and performance of cell edge users. The Multiple User-Multiple Input Multiple Output (MU-MIMO) technology is adopted in a CoMP system so that multiple User Equipments (UEs) are served simultaneously in a multi-cell collaboration manner, which improves the system average throughput and improves an edge throughput by using inter-cell interference suppression. Therefore, application of the MU-MIMO under the CoMP system is a hot technology at present. Critical issues studied in the MU-MIMO technology under the CoMP system include how to support a demodulation pilot sequence collaboratively transmitted in multiple cells and interference suppression between multiple users.
In an existing MU-MIMO transmission mode based on non-codebook precoding, the base station precodes the service data and the pilot sequence Demodulation Reference Signals (DM-RS) and transmits them. The DM-RS is used in channel estimation of the receiver. At the receiver, channel estimation is performed for the DM-RS to obtain a channel estimation value required for data demodulation, and corresponding data demodulation is performed according to the channel estimation value to obtain the service data.
In the prior art, a user must obtain channel estimation of the equivalent channel by estimating the DM-RS, which requires that the DM-RS s of different layers/users must be orthogonal. In the CoMP system, an existing DM-RS does not support orthogonality between cells. Therefore, the existing DM-RS fails to support the MU-MIMO mode of the CoMP system well. When the existing DM-RS is adopted under the MU-MIMO mode of the CoMP system, channel estimation accuracy of the receiver is relatively poor and interference between multiple users can hardly be eliminated, which results in a low signal to interference plus noise ratio of the received signals.